A method for the measurement of collagen fibre diameter in human skin is described. Photographic reduction of electron micrograph negatives onto positive transparency film allows the use of a Quantimet 720 image analysis system for relatively rapid determination of mean collagen fibre diameter based upon the mean cross‐sectional area of a single electron microscope field. The mean collagen fibre diameter from papillary and reticular dermis in normal skin was 56.2 ± 2.5 nm and 62.8 ± 4.3 nm respectively, and exhibited slightly skewed Unimodal distributi